The dielectric constant of irregularly shaped samples, or collections of small pieces of a sample type, often cannot be measured. This is because the conversion of a capacitance measurement to a dielectric constant requires exact knowledge of sample dimensions.
A number of cumbersome and notably inaccurate methods of estimating the dielectric constant of samples with complex geometry are currently used. But, their shortcomings are widely acknowledged and are often not utilized because of their questionable results. These methods require the application of assumptions concerning the additivity of dielectric constants of mixtures when the sample is mixed with materials such as epoxy resins in proportions which must be known with precision.